Certain di- and mono-esters of probucol have been disclosed in U.S. Pat. No. 5,262,439 ('439), assigned to Atherogenics. Mono-esters and mono-ethers of probucol are also disclosed in U.S. Pat. Nos. 6,147,250 ('250) and U.S. Pat. No. 6,121,319 ('319), also assigned to Atherogenics. These mono-esters and mono-ethers have been shown to have significant biological activity against cardiovascular and inflammatory diseases. These compounds and others of the '250 patent are not known to be readily soluble in water. Although not a completely accurate measure of drug absorption, poor water solubility is frequently correlated to low drug absorption and bioavailability.
A series of French patents disclose that certain probucol derivatives are hypocholesterolemic and hypolipemic agents: Fr 2168137 (bis 4hydroxyphenylthioalkane esters); Fr 2140771 (tetralinyl phenoxy alkanoic esters of probucol); Fr 2140769 (benzofuryloxyalkanoic acid derivatives of probucol); Fr 2134810 (bis-(3-alkyl-5-t-alkyl-4-thiazole-5-carboxy)phenylthio)alkanes; FR 2133024 (bis-(4-nicotinoyloxyphenylthio)propanes; and Fr 2130975 (bis(4-phenoxyalkanoyloxy)phenylthio)alkanes).
U.S. Pat. No. 5,155,250 to Parker, et al. discloses that 2,6-dialkyl-4-silylphenols are antiatherosclerotic agents. The same compounds are disclosed as serum cholesterol lowering agents in PCT Publication No. WO 95/15760, published on Jun. 15, 1995. U.S. Pat. No. 5,608,095 to Parker, et al. discloses that alkylated-4-silyl-phenols inhibit the peroxidation of LDL, lower plasma cholesterol, and inhibit the expression of VCAM-1, and thus are useful in the treatment of atherosclerosis.
A series of European patent applications to Shionogi Seiyaku Kabushiki Kaisha disclose phenol esters for use in treating arteriosclerosis. European Patent Application No. 348 203 discloses phenolic thioethers which inhibit the denaturation of LDL and the incorporation of LDL by macrophages. The compounds are useful as anti-arteriosclerosis agents. Hydroxamic acid derivatives of these compounds are disclosed in European Patent Application No. 405 788 and are useful for the treatment of arteriosclerosis, ulcer, inflammation and allergy. Carbamoyl and cyano derivatives of the phenolic thioethers are disclosed in U.S. Pat. No. 4,954,514 to Kita, et al.
WO 01/70757 filed by AtheroGenics, Inc. and published on Sep. 27, 2001, describes the use of certain thioethers of the following formula, and pharmaceutically acceptable salts thereof: 
wherein                a) Ra, Rb, Rc, and Rd are independently any group that does not adversely affect the desired properties of the molecule, including hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkaryl, substituted alkaryl, aralkyl, or substituted aralkyl; and        b) Z is (i) a substituted or unsubstituted carbohydrate, (ii) a substituted or unsubstituted alditol, (iii) C1-10alkyl or substituted C1-10alkyl, terminated by sulfonic acid, (iv) C1-10alkyl or substituted C1-10alkyl, terminated by phosphonic acid, (v) substituted or unsubstituted C1-10alkyl-O—C(O)—C1-10alkyl, (vi) straight chained polyhydroxylated C3-10 alkyl; (vii)—(CR2)1-6-COOH, wherein R is independently hydrogen, halo, amino, or hydroxy, and wherein at least one of the R substituents is not hydrogen; or (viii)—(CR2)1-6-X, wherein X is aryl, heteroaryl, or heterocycle, and R is independently hydrogen, halo, amino, or hydroxy.        
Meng et al., discloses a series of phenolic compounds that have been discovered as potent inhibitors of TNF-α-inducible expression of vascular cell adhesion molecule-1 (VCAM-1) with concurrent antioxidant and lipid-modulating properties. The compounds disclosed have demonstrated efficacies in animal models of atherosclerosis and hyperlipidemia. (Novel Phenolic Antioxidants As Multifunctional Inhibitors Of Inducible VCAM-1 Expression For Use In Atherosclerosis, Bioorganic & Med. Chem Ltrs. 12(18), 2545-2548, 2002).
Sundell et al., discloses a novel metabolically stable phenolic antioxidant compound derived from probucol. ([4-[[1-[[3,5-bis(1,1-dimethylethyl)-4-hydroxypehenyl]thio]-1-methylethyl]thio]2,6-bis (1,1-dimethylethyl) phenoxy]acetic acid) inhibits TNF-α-stimulated endothelial expression of VCAM-1 and MCP-1, two redox-sensitive inflammatory genes critical for the recruitment of leukocytes to joints in rheumatoid arthritis (RA), to a greater extent than ICAM-1. (AGIX-4207: A Novel Antioxidant And Anti-Inflammatory Compound Inhibits Progression Of Collagen II Arthritis In The Rat, FASEB Journal Vol. 16, November 4, PP. A182, Mar. 20, 2002. Apr. 20-24, 2002, Annual Meeting of the Professional Research Scientists on Experimental Biology, ISSN 0892-6638).
Given that certain probucol ester and ether derivatives are of strong commercial importance for the treatment of cardiovascular and inflammatory conditions in humans, it would be useful to increase the bioavailability and pharmacokinetics of these compounds.
It is therefore an object of the present invention to increase the bioavailability of therapeutically useful probucol esters and ethers.
It is a further object of the present invention to enhance the pharmacokinetic properties of therapeutically useful probucol esters and ethers.